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Fedchenko O, Minár J, Akashdeep A, D’Souza SW, Vasilyev D, Tkach O, Odenbreit L, Nguyen Q, Kutnyakhov D, Wind N, Wenthaus L, Scholz M, Rossnagel K, Hoesch M, Aeschlimann M, Stadtmüller B, Kläui M, Schönhense G, Jungwirth T, Hellenes AB, Jakob G, Šmejkal L, Sinova J, Elmers HJ. Observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO 2. SCIENCE ADVANCES 2024; 10:eadj4883. [PMID: 38295181 PMCID: PMC10830110 DOI: 10.1126/sciadv.adj4883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024]
Abstract
Altermagnets are an emerging elementary class of collinear magnets. Unlike ferromagnets, their distinct crystal symmetries inhibit magnetization while, unlike antiferromagnets, they promote strong spin polarization in the band structure. The corresponding unconventional mechanism of time-reversal symmetry breaking without magnetization in the electronic spectra has been regarded as a primary signature of altermagnetism but has not been experimentally visualized to date. We directly observe strong time-reversal symmetry breaking in the band structure of altermagnetic RuO2 by detecting magnetic circular dichroism in angle-resolved photoemission spectra. Our experimental results, supported by ab initio calculations, establish the microscopic electronic structure basis for a family of interesting phenomena and functionalities in fields ranging from topological matter to spintronics, which are based on the unconventional time-reversal symmetry breaking in altermagnets.
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Affiliation(s)
- Olena Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Jan Minár
- University of West Bohemia, New Technologies Research Center, Plzen 30100, Czech Republic
| | - Akashdeep Akashdeep
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Sunil Wilfred D’Souza
- University of West Bohemia, New Technologies Research Center, Plzen 30100, Czech Republic
| | - Dmitry Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Olena Tkach
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
- Sumy State University, Rymski-Korsakov 2, 40007 Sumy, Ukraine
| | - Lukas Odenbreit
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Quynh Nguyen
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | | | - Nils Wind
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Lukas Wenthaus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Markus Scholz
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Moritz Hoesch
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Martin Aeschlimann
- Universität Kaiserslautern, Department of Physics, 67663 Kaiserslautern, Germany
| | - Benjamin Stadtmüller
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Mathias Kläui
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Gerd Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Tomas Jungwirth
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnick’a 10, Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, NG7 2RD Nottingham, UK
| | - Anna Birk Hellenes
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Gerhard Jakob
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnick’a 10, Praha 6, Czech Republic
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnick’a 10, Praha 6, Czech Republic
| | - Hans-Joachim Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128 Mainz, Germany
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Usachov DY, Glazkova D, Tarasov AV, Schulz S, Poelchen G, Bokai KA, Vilkov OY, Dudin P, Kummer K, Kliemt K, Krellner C, Vyalikh DV. Estimating the Orientation of 4f Magnetic Moments by Classical Photoemission. J Phys Chem Lett 2022; 13:7861-7869. [PMID: 35977384 DOI: 10.1021/acs.jpclett.2c02203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
To use efficiently the magnetic functionalities emerging at the surfaces or interfaces of novel lanthanides-based materials, there is a need for complementary methods to probe the atomic-layer resolved magnetic properties. Here, we show that 4f photoelectron spectroscopy is highly sensitive to the collective orientation of 4f magnetic moments and, thus, a powerful tool for characterizing the related properties. To demonstrate this, we present the results of systematic study of a family of layered crystalline 4f-materials, which are crystallized in the body-centered tetragonal ThCr2Si2 structure. Analysis of 4f spectra indicates that the 4f moments at the surface experience a strong reorientation with respect to the bulk, caused by changes of the crystal-electric field. The presented database of the computed 4f spectra for all trivalent rare-earth ions in their different MJ states will facilitate the estimation of the orientation of the 4f magnetic moments in the layered 4f-systems for efficient control of their magnetic properties.
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Affiliation(s)
- Dmitry Yu Usachov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Daria Glazkova
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Artem V Tarasov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Susanne Schulz
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Georg Poelchen
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01062 Dresden, Germany
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Kirill A Bokai
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Oleg Yu Vilkov
- St. Petersburg State University, 7/9 Universitetskaya nab, St. Petersburg 199034, Russia
| | - Pavel Dudin
- Synchrotron-SOLEIL, Saint-Aubin, BP48, 91192 Gif-sur-Yvette, France
| | - Kurt Kummer
- European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Kristin Kliemt
- Kristall-und Materiallabor, Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue Strasse 1, D-60438 Frankfurt am Main, Germany
| | - Cornelius Krellner
- Kristall-und Materiallabor, Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue Strasse 1, D-60438 Frankfurt am Main, Germany
| | - Denis V Vyalikh
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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van der Laan G, Figueroa AI. X-ray magnetic circular dichroism—A versatile tool to study magnetism. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.03.018] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Heinzmann U, Dil JH. Spin-orbit-induced photoelectron spin polarization in angle-resolved photoemission from both atomic and condensed matter targets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:173001. [PMID: 22480989 DOI: 10.1088/0953-8984/24/17/173001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The existence of highly spin polarized photoelectrons emitted from non-magnetic solids as well as from unpolarized atoms and molecules has been found to be very common in many studies over the past 40 years. This so-called Fano effect is based upon the influence of the spin-orbit interaction in the photoionization or the photoemission process. In a non-angle-resolved photoemission experiment, circularly polarized radiation has to be used to create spin polarized photoelectrons, while in angle-resolved photoemission even unpolarized or linearly polarized radiation is sufficient to get a high spin polarization. In past years the Rashba effect has become very important in the angle-resolved photoemission of solid surfaces, also with an observed high photoelectron spin polarization. It is the purpose of the present topical review to cross-compare the spin polarization experimentally found in angle-resolved photoelectron emission spectroscopy of condensed matter with that of free atoms, to compare it with the Rashba effect and topological insulators to describe the influence and the importance of the spin-orbit interaction and to show and disentangle the matrix element and phase shift effects therein.The relationship between the energy dispersion of these phase shifts and the emission delay of photoelectron emission in attosecond-resolved photoemission is also discussed. Furthermore the influence of chiral structures of the photo-effect target on the spin polarization, the interferences of different spin components in coherent superpositions in photoemission and a cross-comparison of spin polarization in photoemission from non-magnetic solids with XMCD on magnetic materials are presented; these are all based upon the influence of the spin-orbit interaction in angle-resolved photoemission.
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Affiliation(s)
- Ulrich Heinzmann
- Faculty of Physics, University of Bielefeld, Universitätsstrasse, D-33501 Bielefeld, Germany.
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Haverkort MW, Hu Z, Tanaka A, Ghiringhelli G, Roth H, Cwik M, Lorenz T, Schüssler-Langeheine C, Streltsov SV, Mylnikova AS, Anisimov VI, de Nadai C, Brookes NB, Hsieh HH, Lin HJ, Chen CT, Mizokawa T, Taguchi Y, Tokura Y, Khomskii DI, Tjeng LH. Determination of the orbital moment and crystal-field splitting in LaTiO3. PHYSICAL REVIEW LETTERS 2005; 94:056401. [PMID: 15783666 DOI: 10.1103/physrevlett.94.056401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Indexed: 05/24/2023]
Abstract
Utilizing a sum rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO3 is strongly reduced from its ionic value, both below and above the Ne el temperature. Using Ti L2,3 x-ray absorption spectroscopy as a local probe, we found that the crystal-field splitting in the t2g subshell is about 0.12-0.30 eV. This large splitting does not facilitate the formation of an orbital liquid.
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Affiliation(s)
- M W Haverkort
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
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Mizokawa T, Tjeng LH, Sawatzky GA, Ghiringhelli G, Tjernberg O, Brookes NB, Fukazawa H, Nakatsuji S, Maeno Y. Spin-orbit coupling in the Mott insulator Ca(2)RuO(4). PHYSICAL REVIEW LETTERS 2001; 87:077202. [PMID: 11497913 DOI: 10.1103/physrevlett.87.077202] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2000] [Indexed: 05/23/2023]
Abstract
O 1s x-ray absorption study of the Mott insulator Ca(2)RuO(4) shows that the orbital population of the 4d t(2g) band dramatically changes with temperature. In addition, spin-resolved circularly polarized photoemission study of Ca(2)RuO(4) shows that a substantial orbital angular momentum is induced in the Ru 4d t(2g) band. Based on the experimental results and model Hartree-Fock calculations, we argue that the cooperation between the strong spin-orbit coupling in the Ru 4d t(2g) band and the small distortion of the RuO(6) octahedra causes the interesting changeover of the spin and orbital anisotropy as a function of temperature.
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Affiliation(s)
- T Mizokawa
- Department of Complexity Science and Engineering, University of Tokyo, Tokyo 113-0033, Japan
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Thole BT. X-ray-absorption sum rules in jj-coupled operators and ground-state moments of actinide ions. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:14458-14469. [PMID: 9983244 DOI: 10.1103/physrevb.53.14458] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kuch W, Dittschar A, Meinel K, Zharnikov M, Schneider CM, Kirschner J, Henk J, Feder R. Magnetic-circular-dichroism study of the valence states of perpendicularly magnetized Ni(001) films. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:11621-11630. [PMID: 9982785 DOI: 10.1103/physrevb.53.11621] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Thole BT. Spin polarization and magnetic dichroism in photoemission from core and valence states in localized magnetic systems. IV. Core-hole polarization in resonant photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:15355-15363. [PMID: 9980892 DOI: 10.1103/physrevb.52.15355] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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12
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Nicklin CL, Binns C, Mozley S, Norris C, Alleno E, Barthés-Labrousse MG. Resonant photoemission spectra at the 4f and 5p levels of Tm across the 4d-4f absorption threshold. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:4815-4822. [PMID: 9981663 DOI: 10.1103/physrevb.52.4815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Arenholz E, Navas E, Starke K, Baumgarten L, Kaindl G. Magnetic circular dichroism in core-level photoemission from Gd, Tb, and Dy in ferromagnetic materials. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:8211-8220. [PMID: 9977431 DOI: 10.1103/physrevb.51.8211] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kuch W, Lin M, Steinhögl W, Schneider CM, Venus D, Kirschner J. Angle-resolved study of magnetic dichroism in photoemission using linearly polarized light. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:609-612. [PMID: 9977128 DOI: 10.1103/physrevb.51.609] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Cherepkov NA. Origin of magnetic dichroism in angular-resolved photoemission from ferromagnets. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:13813-13816. [PMID: 9975588 DOI: 10.1103/physrevb.50.13813] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Thole BT. Magnetic ground-state properties and spectral distributions. II. Polarized photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:11474-11483. [PMID: 9975277 DOI: 10.1103/physrevb.50.11474] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Henk J, Halilov SV, Scheunemann T, Feder R. Magnetic linear dichroism and spin polarization in 3d-band photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:8130-8133. [PMID: 9974828 DOI: 10.1103/physrevb.50.8130] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Starke K, Baumgarten L, Arenholz E, Navas E, Kaindl G. Magnetic circular dichroism in 4f photoemission from terbium. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:1317-1320. [PMID: 9975813 DOI: 10.1103/physrevb.50.1317] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Thole BT. Spin polarization and magnetic dichroism in photoemission from core and valence states in localized magnetic systems. III. Angular distributions. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:9613-9631. [PMID: 10009761 DOI: 10.1103/physrevb.49.9613] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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